Supported Disk formats in ESX

The supported disk formats in ESX are:

  • zeroedthick (default) – Space required for the virtual disk is allocated during the creation of the disk file. Any data remaining on the physical device is not erased during creation, but is zeroed out on demand at a later time on first write from the virtual machine. The virtual machine does not read stale data from disk.
  • eagerzeroedthick – Space required for the virtual disk is allocated at creation time. In contrast to zeroedthick format, the data remaining on the physical device is zeroed out during creation. It might take much longer to create disks in this format than to create other types of disks.
  • thick – Space required for the virtual disk is allocated during creation. This type of formatting does not zero out any old data that might be present on this allocated space. A non-root user cannot create disks of this format.
  • thin – Space required for the virtual disk is not allocated during creation, but is supplied and zeroed out, on demand at a later time.
  • rdm – Virtual compatibility mode for raw disk mapping.
  • rdmp – Physical compatibility mode (pass-through) for raw disk mapping.
  • raw – Raw device.
  • 2gbsparse – A sparse disk with 2GB maximum extent size. You can use disks in this format with other VMware products, however, you cannot power on sparse disk on a ESX host till you reimport the disk with vmkfstools in a compatible format, such as thick or thin.
  • monosparse – A monolithic sparse disk. You can use disks in this format with other VMware products.
  • monoflat – A monolithic flat disk. You can use disks in this format with other VMware products.
Use these commands to create a virtual disk:

vmkfstools
-c –createvirtualdisk [kK|mM|gG]-a –adaptertype [buslogic|lsilogic]
-d –diskformat [thin|zeroedthick|eagerzeroedthick]

For more information, see the ESX Configuration Guide section vSphere Basic System Administration.


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